SpiceDisplay: validate 'self' argument for public API
SpiceDisplay: validate 'self' argument for public API

Add defensive g_return[_val]_if_fail(SPICE_IS_DISPLAY()) to all public API

Fantu/spice-gtk,guodong/spice-gtk,elmarco/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,flexVDI/spice-gtk,guodong/spice-gtk,elmarco/spice-gtk,SPICE/spice-gtk,fgouget/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,SPICE/spice-gtk,fgouget/spice-gtk,SPICE/spice-gtk,Fantu/spice-gtk,guodong/spice-gtk,guodong/spice-gtk,Fantu/spice-gtk,elmarco/spice-gtk,SPICE/spice-gtk,fgouget/spice-gtk,flexVDI/spice-gtk,Fantu/spice-gtk,elmarco/spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk,freedesktop-unofficial-mirror/spice__spice-gtk